The detection of hazardous events is a useful practice to warn the public as well as to inform safety and security forces as to the existence of the hazardous event. Hazardous events can occur naturally, such as in the case of a hurricane, tornado or earthquake, or can occur through a human event such as in an accidental chemical spill or in a terrorist attack. At the present time there are some early warning systems in place to provide the potentially affected populace and the relevant emergency forces with some advance notice of some disasters. For example, a system of Doppler radar installations in various communities can provide in some cases a timely warning of impending high winds and possible tornadoes. This system is limited to one particular type of anomaly, i.e., high winds, and is only partially effective because it relies on early warning sirens and broadcast media, both of which have limitations, for communication.
U.S. Pat. No. 6,169,476 to Flanagan discloses an early warning system for natural and human initiated disasters. Flanagan's system collects and analyzes data as the disasters occur, and when necessary, transmits early warnings to cause mitigation responses to lessen the disaster's impact on lives and property. The system uses a plurality of sensing, detecting and reporting sources, some of which are automatic and some of which are human originated. A central processing site receives this data and determines the type, magnitude, speed, direction and expected geographic area to be affected by the anomaly. A plurality of cell relays is disposed across a geographic area covered by the system. Once the central processing apparatus receives the data from the sensors and assesses the likely or potential outcome, a warning signal is transmitted to selected cell relays for re-broadcast to the intended receivers, which could include television, radio, cell phones, pagers, and various types of alarms. The system determines which cell relays will receive the warning signals based on the expected geographic area to be affected by the disaster, thereby only alerting those in the projected path of the threat.
Graviton, Inc. of La Jolla, Calif. has proposed an end-to-end wireless sensing and network system that provides a self-organizing and self-healing capability so that the system could survive and continue to function even if certain sensors were rendered dysfunctional. Graviton's sensors include a low-cost processor, and support a large array of sensor devices. One proposed use for Graviton's system includes homeland security. Multiple sensor nodes communicate bi-directionally, initially to a data hub. The system's modular approach allows applications (data collection, data mining, analysis, actuation) to be distributed throughout the network. Graviton's wireless distributed sensory network involves continually connecting and reconnecting between local points and far flung nodes.
Hansler in U.S. Pat. No. 5,831,526 discloses a network of hazard detectors where each detector communicates a locally hazardous condition to multiple neighboring detectors using radio frequency (RF) signals. Hansler's primary embodiment involves multiple smoke alarms in a building.
Improved communication systems for hazardous or environmental anomalies can be useful in the management of the safety and security of buildings, as well in the transportation industry. Also, better network communications would be useful in the area of process controls for such commercial and industrial areas as manufacturing, utilities and infrastructure monitoring.
It would be advantageous if there could be developed an improved sensor network and communication system.